The present invention relates generally to refrigeration systems and methods, and is particularly concerned with an electrochemical refrigeration system and method for use in removing relatively small heat loads.
A conventional refrigeration system uses a mechanical compressor of the piston or rotary type to compress a refrigeration gas or vapor, which is subsequently expanded, and sometimes vaporized, utilizing energy available at low temperatures, and thereby cooling or maintaining an area such as a refrigeration chamber, a surface, or a fluid, at a low temperature. Thus, in a basic refrigeration cycle, refrigerant is compressed in a mechanical compressor. The compressed vapor is then liquefied in a condenser. Liquid refrigerant flows from the condenser to an expansion valve where its pressure and temperature are reduced, and then to an evaporator where heat is absorbed from the region or fluid being cooled and the refrigerant boils. The liquid refrigerant is thus evaporated and then returned to the compressor to repeat the refrigeration cycle.
There are a number of problems with conventional mechanical refrigeration systems. One is that mechanical compressors typically require considerable maintenance to ensure adequate lubrication, to replace seals, and so on. Furthermore, the efficiency of mechanical compressors is considerably reduced when the compressor size is decreased to process small heat loads, generally below the power levels of small domestic refrigerators from the "white goods" industry, i.e. rated generally at the ton level, which is equivalent to a heat load of 3.5 kilowatts. Because of the unsuitability of mechanical compressors for handling small heat loads, microrefrigerators for heat loads of 50-100 watts, or less than 1 kilowatt, are not available. Thus, other means must be used for cooling when small heat loads are involved, such as fans, metal plates with fins as heat sinks. and the like, and these are often subject to other disadvantages. Up to now, no refrigeration system has been devised which is suitable for handling small heat loads of less than 1 kilowatt.
In my previous U.S. Pat. Nos. 3,489,670, 4,118,299, 4,402,817, 4,522,698, 4,648,955, 5,038,821, 5,149,413, 5,334,304, and 5,417,822, and in the following publications: Maget H., Proceedings of the 5.sup.th Annual Battery Conference on Applications and Advances, Long Beach, Calif., Jan. 1990 "Electrochemical Prime Movers, Converters of DC Electric Energy to Mechanical Work"; Maget H., "Electrochemical Prime Movers", 24.sup.th IECEC, Washington, D.C. Aug. 1989, Vol. 3, pp 1613-1618; and Maget H., Proceedings of the Symposium on Fuel Cells, San Francisco, Calif. No. 1989, Vol 89-14, pp 94-105 "Electrochemical Pumps Offsprings of SPE Fuel Cell Technology", I have described various low pressure actuators used for pumping fluids in various applications, and means for operation and control of such actuators.